serial_crusher:unless you spend so much time vetting each app you install that you're completely confident it's legitimate and virus-free

You know who spends so much time vetting every app I install that I'm completely confidant it's legitimate and virus-free? Apple, that's who.

And this is why Apple's app store is a tenth of the size of Google Play.

Also, I have some serious doubts about just how many viruses are actually out there and how easy they are to get. All of these apps come with a comments and rating system. If it comes with a virus, it's going to to advertised well before you download it. Viruses are also highly illegal, so if you're passing an app as a virus, then your name is going to be all over it.

Finally, a pet peeve:

There are two primary types of Android viruses: Trojans, which send SMS messages to premium numbers, and spyware, which sends information-contacts, for instance-from the phone to the spyware's developer.

Sorry, but nether of these are "viruses". Viruses copy themselves and infect other devices. At best, these are collectively "malware".